Advice on getting a 2nd dog

Hi! I wasn't sure what section to put this in. I currently have an almost 3 year old male chocolate Labrador (neutered) and am looking to get a second dog. I was originally set on getting a German Shepherd because I've wanted one since I was a child and I want that intimidation factor when I have the dogs out by myself or am home alone. My lab just wags his tail at strangers. But I've been wondering if a shepherd is right for me. I keep seeing mixed information online about just how much exercise, and grooming they need. So I'm also considering just getting another Labrador. Either way will be getting a female dog.

Some places say they have twice the amount of energy of a lab (requiring hours of activity daily), some say less, and some say they are about the same. My lab currently is good with around at least 40-50 minutes of activity a day (typically half-an-hour walk when I get home from work, then play time in the evening an hour and a half after his dinner). On the weekends he typically gets two or three half-an-hour walks, plus play time as I am home all day.

I know with two dogs, both will get more activity as they will play together, I'm just wondering if a shepherd would require hours-long walks, then plus play time, to be calm.

As for grooming, I don't really have time to brush a dog more than once a week. That's how often I brush my lab. Do shepherds require more grooming than that? I'm looking for a short-coat, not long.

Also, how are shepherd puppies? When I brought my lab home he just settled in right away. He didn't really whine or scream when crated, wasn't afraid of the cat, and was pretty easy to train. He was destructive, but that's just typical puppy.

I also have anxiety, and someone told me that shepherds aren’t good for people with anxiety because they will see everyone as a threat. Is that true, or an over-exaggeration?